[Extensions] Isolate ExtensionFunction results_ and error_

extensions/browser/quota_service_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/process/process.h"
 #include "base/run_loop.h"
@@ skipping 48 matching lines @@
  public:
   void GetBucketsForArgs(const base::ListValue* args,
                          BucketList* buckets) override {}
 };
 
 class MockFunction : public ExtensionFunction {
  public:
   explicit MockFunction(const char* name) { set_name(name); }
 
   void SetArgs(const base::ListValue* args) override {}
-  std::string GetError() const override { return std::string(); }
   void SetError(const std::string& error) override {}
   void Destruct() const override { delete this; }
   ResponseAction Run() override { return RespondLater(); }
 
  protected:
   ~MockFunction() override {}
 };
 
 class TimedLimitMockFunction : public MockFunction {
  public:
@@ skipping 244 matching lines @@
   EXPECT_NE("", service_->Assess(extension_a_, f.get(), &arg,
                                  kStartTime + TimeDelta::FromDays(1) +
                                      TimeDelta::FromSeconds(25)));
 
   // Like now.
   EXPECT_EQ("", service_->Assess(extension_a_, f.get(), &arg,
                                  kStartTime + TimeDelta::FromDays(2)));
 }
 
 }  // namespace extensions